Various arrangements of apparatus are known for extracting contaminants from a contaminated gas flow.
These arrangements are highly diversified, and are constructed to meet the degree of extraction desired and to suit the nature of the contaminants concerned.
For example, when the contaminants concerned consist of finely divided, discrete solid dust particles, it has earlier been proposed to provide barrier filters, so-called hose filters, where the contaminated gas flow is forced to pass through fine-mesh fabric hoses, in which the solid contaminants adhere to the hoses and a cleansed gas flow exits therefrom.
It is also known to extract solid contaminants from a contaminated gas flow in an electrostatic dust precipitator, in which the gas flow is passed through an electric field so as to electrically charge the solid particles contained in the gas, these charged particles being attracted to a collecting electrode.
The prior art in this field also includes various methods and apparatus for separating both solid contaminants and gaseous contaminants from a contaminated gas flow.
A common example of such apparatus or arrangements are those in which a contaminated gas flow is passed through various kinds of gas scrubbers, in which the contaminated gas is caused to bubble through a liquid bath, or is sprayed with liquid droplets arranged to fall through the flow of gas, normally in counter-flow therewith, or in which liquid is finely dispersed in the gas flow, so as to obtain an agglomerating effect between dust particles and water particles, the larger particles or agglomerates being subsequently extracted from the gas flow in a so-called cyclone, by centrifugation.
It is also known that condensable gaseous contaminants can be extracted from a contaminated gas flow, by causing the contaminants to condense against cooling surfaces specifically constructed herefor and brought to a temperature at which condensation will take place, or by causing the contaminants to condense on cold liquid droplets, which are subsequently removed from the system in a known manner.
In the case of gas flows contaminated with both solid dust particles and gaseous contaminants, it is also known in the art to first separate the solid particles from the gas flow and then to separate the gaseous contaminants from the gas flow that has been cleansed of solid particles, by causing the gaseous contaminants to react with an absorption material, and then to separate the reacted absorption material in a known manner.